Eu paguei pelo curso de português ontem.

Yes. In Brazilian Portuguese, subject pronouns are often omitted when the verb already makes the subject clear.

So:

• Eu paguei pelo curso de português ontem.
• Paguei pelo curso de português ontem.

Both are natural.

Including eu can add emphasis, contrast, or clarity. For example, if you want to stress that I paid, not someone else, then eu is useful.

Paguei is the preterite form of pagar.

In Brazilian Portuguese, the preterite is commonly used for a completed action in the past. Here, it means the payment happened and is finished.

• pagar = to pay
• paguei = I paid

This is one of the most common past tenses in everyday speech.

This is a spelling change used to keep the correct sound.

The verb is pagar. If Portuguese wrote pagei, the g would sound like the g in English genre. But in pagar, the g has a hard sound, like in go.

So Portuguese adds u before e:

• pagar
• eu paguei

That keeps the hard g sound.

This also happens in other verbs ending in -gar, such as:

• chegar → cheguei
• carregar → carreguei

Pelo is a contraction of:

• por + o = pelo

In this sentence, it appears because pagar is often used with por when you mean pay for something:

• pagar por algo = to pay for something

So:

• paguei por o curso would be wrong as a full form in normal usage
• it contracts to paguei pelo curso

Since curso is masculine singular, the article is o, so the contraction becomes pelo.

Related forms:

• pela = por + a
• pelos = por + os
• pelas = por + as

Yes, you may hear that too.

In Portuguese, pagar can be used in more than one way:

• pagar o curso
• pagar pelo curso

Both can mean that you paid for the course.

Very broadly:

• pagar o curso can sound a bit more direct
• pagar pelo curso clearly highlights the idea of paying for it

In real Brazilian Portuguese, both are used, and the difference is often small in everyday conversation.

Portuguese often uses noun + de + noun where English might use an adjective or a noun used like an adjective.

So:

• curso de português = Portuguese course
• literally, something like course of Portuguese

This pattern is extremely common:

• livro de história = history book
• professor de inglês = English teacher
• aula de matemática = math class

So de português is the normal way to say what kind of course it is.

In Portuguese, names of languages are normally not capitalized, unlike in English.

So:

• português
• inglês
• espanhol

That is why curso de português uses lowercase português.

You would also normally write:

• Eu estudo português.

The accent in português shows the stressed syllable and helps distinguish the word’s pronunciation.

The stress falls on the final syllable:

• por-tu-guês

Without the accent, the pronunciation rules would suggest a different stress pattern.

The ending -ês is common in nationality/language words such as:

• português
• inglês
• francês

Putting ontem at the end is very natural, but Portuguese word order is flexible.

All of these are possible:

• Eu paguei pelo curso de português ontem.
• Ontem eu paguei pelo curso de português.
• Eu ontem paguei pelo curso de português. (possible, but less neutral)

The version with ontem at the end sounds very normal and neutral in everyday speech.

To express a simple completed action like this, eu paguei is the most natural choice.

Portuguese has other past forms, but they mean different things:

• eu pagava = I used to pay / I was paying
• eu tinha pago = I had paid
• eu tenho pago = I have been paying / I have paid repeatedly, depending on context

For a single finished action yesterday, eu paguei is the best match.

A rough pronunciation guide for an English speaker could be:

• eu ≈ eh-o / yo (depending on accent, very reduced in fast speech)
• paguei ≈ pah-GAY
• pelo ≈ PEH-loo
• curso ≈ KOOR-soo
• de ≈ jee / dee / dji depending on region and speed
• português ≈ por-too-GEHS
• ontem ≈ ON-teng / ON-teen nasalized, depending on accent

A few useful notes:

• The r in curso is not like a strong English r
• Final vowels are often lighter than in English
• em in ontem is nasal

If your goal is speaking naturally, listening to Brazilian audio is much more helpful than relying only on English-style approximations.