"I always paid with my card."
Translation:Je payais toujours avec ma carte.
Adverb placement follows different rules in French and English:
you cannot put an adverb (or anything else) between the subject and the verb, with the exception of 'ne' and object pronouns.
The only natural-sounding placement of toujours in this sentence is right after the verb (if the verb has an auxiliary, it will be placed between the auxiliary and the verb): Je payais toujours, or J'ai toujours payé