Invoice without signature

Hello, I bought a bicycle from a private person. The lady in question only wanted to issue a receipt: Gazelle bicycle sold on 21 May 25 for €60 in Geel, paid. She did not want to sign it or write her name and address. She said that this was not necessary and that she had been running a company for years. Can I still claim this as an expense and write it off afterwards? This is because it is a purchase for sale. Thank you in advance for your answers.